Peer Revenue Past citations are no guarantee of future returns

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 2 December

Astrophysics of Galaxies

An Ancient Descendant of the First Galaxies

Jacqueline Antwi-Danso, Adam Muzzin, Luke Robbins et al. (+18 more)

JWST has revealed unexpectedly bright galaxies in the first 500 Myr after the Big Bang. Their overabundance suggests that they are preferentially observed during burst phases, where their star formation rates increase dramatically. In cosmological simulations, such bursts transition into short ($\approx 40$ Myr) periods without star formation or naps. Using JWST/NIRCam medium-band observations, we report the discovery of the galaxy CANUCS-A370-2228423 ($z = 5.95 \pm 0.06$, $\log(M_\ast/M_{\odot}) = 9.14 \pm 0.09$), dubbed The Sleeper. Its star formation history indicates rapid assembly in the first 300 Myr ($z \gtrsim 14$), where it formed a $\log(M_\ast/M_{\odot}) = 8.7^{+0.3}_{-0.4}\ M_{\odot}$ progenitor, comparable in stellar mass to the few spectroscopically confirmed galaxies at those redshifts. Unexpectedly, this is followed by several hundred million years of suppressed star formation, in stark contrast to nappers. This results in a remarkably strong hydrogen Balmer break, exceeding that of any galaxy observed within the first billion years by a factor of $\approx 3$. Furthermore, Sleeper-like systems are overabundant in the observed survey volume compared to theory, as the probability of finding such galaxies in simulations is $< 0.2\%$. The discovery of The Sleeper therefore disrupts the current narrative that all luminous galaxies in the first few hundred million years grow into massive descendants. Instead it presents an alternative evolutionary pathway in which these unusually luminous galaxies fade into inefficient dwarfs after an early starburst, revealing greater diversity in the first stages of galaxy evolution.
Read the full abstract

All authors Jacqueline Antwi-Danso, Adam Muzzin, Luke Robbins, Yoshihisa Asada, Danilo Marchesini, Marcin Sawicki, Kartheik Iyer, Kate Whitaker, Joshua Speagle, Casey Papovich, Chris Willott, Maruša Bradač, Guillaume Desprez, Vladan Markov, Nicholas Martis, Gaël Noirot, Ghassan Sarrouh, Rahul Kannan, Roberto Abraham, Seiji Fujimoto, Katherine Myers

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Inferring black hole formation channels in GWTC-4.0 via parametric mass-spin correlations derived from first principles

Emanuele Berti, Francesco Crescimbeni, Gabriele Franciolini et al. (+3 more)

We investigate the differences between several proposed formation scenarios for binary black holes (BBHs), including isolated stellar evolution, dynamical assembly in dense clusters and AGN disks, and primordial BHs. Our approach exploits the predicted spin features of each formation channel, and adopts parameterized models of the predicted correlations between the spin magnitudes (and orientations) and mass, inspired by first principles. Using hierarchical Bayesian inference on the recent GWTC-4.0 dataset, we compare these features across all models and assess how well each scenario explains the data. We find that the data strongly favor the presence of a positive correlation between mass and spin magnitude, in agreement with previous studies. Furthermore, the hierarchical scenario provides a better fit to the observations, due to the inclusion of second-generation mergers leading to higher spins at larger masses. The current dataset is not informative enough about spin orientation: the cluster (random orientations) and AGN (aligned orientations) scenarios have comparable Bayesian evidence. Finally, the mass-spin correlation predicted by the primordial scenario gives a poor fit to the data, and this scenario can only account for a subset of the observed events.
Read the full abstract

All authors Emanuele Berti, Francesco Crescimbeni, Gabriele Franciolini, Simone Mastrogiovanni, Paolo Pani, Grégoire Pierra

Instrumentation and Methods for Astrophysics

Bright Region Reset: an on-detector strategy for minimizing the impacts of atmospheric emission lines on spectral observations

Theodore A. Grosson, Edward L. Chapin, Tim Hardy et al. (+4 more)

Observations in the near-infrared using large ground-based telescopes are adversely impacted by bright atmospheric emission lines, particularly the OH Meinel bands. These lines can saturate a moderate-resolution spectrograph on the order of minutes, resulting in information loss at the wavelengths of the lines. OH lines also vary on similar timescales, requiring frequent sky exposures to be able to subtract the sky spectrum from that of the target. In this paper we present a new method, which we call bright region reset (BRR), to prevent the saturation of these lines in near-infrared spectra while simultaneously improving information about their variability. This is accomplished by periodically resetting pixels that contain bright lines on a detector capable of sub-window readout while the rest of the detector continues integrating. This method is demonstrated on the McKellar Spectrograph in the 1.2 m telescope at the Dominion Astrophysical Observatory in Victoria, Canada. Using a Teledyne H2RG detector, we reset the emission lines produced by an arc lamp while still recording their flux. We show no degradation in the resulting spectrum compared to a conventional observing mode. Unlike other OH line mitigation strategies, the BRR method not only avoids loss of information at wavelengths containing the lines, but also provides higher-cadence information on sky line variability, making it a promising technique for implementation at observatories. We advocate demonstrating this method on sky at existing 8–10 m class facilities with near-infrared spectrographs equipped with HxRG detectors in order to test its feasibility for use in sky subtraction schemes for premier modern spectrographs, including the upcoming generation of instruments for the Extremely Large Telescopes.
Read the full abstract

All authors Theodore A. Grosson, Edward L. Chapin, Tim Hardy, Masen Lamb, Jordan Lothrop, Alan W. McConnachie, Richard Murowinski

Astrophysics of Galaxies

Joint JWST-DECam Lensing Reveals That the Bullet Cluster Is a Minor Merger

Boseong Young Cho, M. James Jee, Hyungjin Joo et al. (+2 more)

We present the first robust virial masses of the Bullet Cluster's three individual components from a joint weak+strong lensing analysis combining JWST/NIRCam and DECam observations. Despite its status as the benchmark system for dark matter and merger studies, inferred mass ratios for the Bullet Cluster have spanned a wide range from $\sim$2:1 to $\gtrsim$10:1 over more than two decades. We revisit this tension through three key advances: (1) JWST's exceptional data quality enables us to resolve three distinct halos, (2) DECam's wide-field coverage beyond its virial radius eliminates the need for extrapolation, and (3) high-fidelity strong-lensing priors mitigate weak-lensing model bias. We obtain $M_{200c} = 15.11^{+2.48}_{-2.10} \times 10^{14}M_{\odot}$ for the main cluster and $1.49^{+0.32}_{-0.25} \times 10^{14}M_{\odot}$ for the subcluster, yielding a mass ratio of $10.14^{+3.22}_{-2.47}$, definitively classifying the Bullet Cluster as a minor merger. This result reconciles the long-standing tension in the mass ratio and provides updated initial parameters for future modeling of this iconic system.
Read the full abstract

All authors Boseong Young Cho, M. James Jee, Hyungjin Joo, Sangjun Cha, Kim HyeongHan

Astrophysics of Galaxies

On the Origin of Gas-stripping of Galaxies in Group Environments

Jinsu Rhee, Christophe Pichon, Yohan Dubois et al. (+12 more)

We investigate how low-mass group environments ($M_{\rm vir} \sim 10^{12-13}\,M_{\odot}$) influence the gas content of their satellite galaxies with $M_* > 10^{7}\,M_{\odot}$ using the \NHtwo\ simulation. Many satellite galaxies preserve substantial gas reservoirs, yet show signs of outer gas stripping, reminiscent of jellyfish galaxies in clusters. In contrast, low-mass satellites ($<10^8 \, M_{\odot}$) are largely gas-deficient, and some of them undergo gas removal within their host group by external pressure triggered by either galaxy interactions or ram pressure exerted by the hot intragroup medium. Complete gas removal in these satellite galaxies occurs when the external hydrodynamic pressure exceeds the gravitational restoring force, typically due to stochastic events such as galaxy-galaxy interaction or nearby galactic outflows. The emergence of a characteristic stellar mass of $10^8 \, M_{\odot}$ which determines the efficiency of gas removal in groups, likely reflects the differing scaling relations of external pressure with halo mass and gravitational restoring force with stellar mass. While tidal interactions can be a significant cause of gas loss in satellite galaxies, those severe enough to affect the gas content in the central regions typically lead to the complete disruption of the galaxy. Consequently, gas loss driven by tidal interactions may be underestimated in the studies focusing solely on surviving galaxies. Group environments, where environmental effects are weaker and satellite galaxies tend to have lower restoring forces due to their low masses, exhibit complex manifestations of gas loss that are not seen in more massive environments such as clusters.
Read the full abstract

All authors Jinsu Rhee, Christophe Pichon, Yohan Dubois, Sukyoung K. Yi, Jongwan Ko, Yun-Kyeong Sheen, San Han, Seyoung Jeon, J. K. Jang, Wonki Lee, Emanuele Contini, Bumhyun Lee, Jaehyun Lee, Katarina Kraljic, Sébastien Peirani

Astrophysics of Galaxies

Infrared emission from $z \sim 6.5$ quasar host galaxies: a direct estimate of dust physical properties

M. Costa, R. Decarli, F. Pozzi et al. (+6 more)

Quasars at the dawn of Cosmic Time ($z>6$) are fundamental probes to investigate the early co-evolution of supermassive black holes and their host galaxy. Nevertheless, their infrared spectral energy distribution remains at the present time poorly constrained, due to the limited photometric coverage probing the far-infrared wavelength range where the dust modified black-body is expected to peak ($\sim80$ $\mathrm{\mu m}$). Here we present a study of the high-frequency dust emission via a dedicated ALMA Band 8 ($\sim$400 GHz) campaign targeting 11 quasar host galaxies at $6<z<7$. Combined with archival observations in other ALMA bands, this program enables a detailed characterization of their infrared emission, allowing for the derivation of dust masses ($M_{d}$), dust emissivity indexes ($\beta$), dust temperatures ($T_{d}$), infrared luminosities ($L_{IR}$), and associated star formation rates (SFRs). Our analysis confirms that dust temperature is on average higher in this sample (34-65 K) if compared to local main-sequence galaxies' values, and that this finding can be linked to the increased star formation efficiency we derive in our work, as also suggested by the [CII]$_{158\mu m}$ deficit. Most remarkably, we note that the average value of $T_d$ of this sample doesn't differ from the one that is observed in luminous, ultra-luminous and hyper-luminous infrared galaxies at different redshifts that show no signs of hosting a quasar. Finally, our findings suggest that the presence of a bright AGN does not significantly bias the derived infrared properties, although further high-frequency, high-spatial resolution observations might reveal more subtle impacts on sub-kiloparsec scales.
Read the full abstract

All authors M. Costa, R. Decarli, F. Pozzi, P. Cox, R. A. Meyer, A. Pensabene, B. P. Venemans, F. Walter, F. Xu

High Energy Astrophysical Phenomena

A Wind-Driven Origin for the Firework Morphology of the Supernova Remnant Pa 30

Eric R. Coughlin, Greg Salvesen and Dheeraj R. Pasham

Pa 30 – the likely remnant of the Galactic type Iax supernova of 1181 AD – displays an unusual, firework-like morphology, consisting of radial filaments extending from a common center, where a white dwarf (WD) currently drives a very fast wind (speed $\gtrsim 10^{4}$ km s$^{-1}$). We propose the filaments arose from the Rayleigh-Taylor-unstable nature of the interface between the circumstellar medium (CSM) and the shocked wind launched by the natal WD; the filaments then elongated intact due to the Kelvin-Helmholtz-stable nature of the large initial density contrast between the wind and CSM, supplemented by the slowly declining wind density profile (relative to homologously expanding ejecta). To support this interpretation, we present two-dimensional hydrodynamical simulations and derive the filament properties, including their speed, density, and temperature, all of which are consistent with observations. We suggest the filaments elongate until the wind and CSM densities become comparable at the contact discontinuity, which occurs within 1–10 years, and then truncate because the RTI halts. The subsequent KHI growth timescale across the current width of the filaments is longer than the age of Pa 30, so they remain intact. The filament-less central region in Pa 30 is therefore more likely a consequence of the finite timescale over which the RTI operates, rather than a wind termination shock. In general, firework-like filaments may form in other systems, provided there is a sufficiently large density contrast between the ejecta and its surroundings.
Read the full abstract

Cosmology and Nongalactic Astrophysics

Cosmology after Phantom Crossing by Horndeski Gravity

Eric V. Linder

One possible way to explain the observed effective dark energy equation of state crossing $w=-1$ (the phantom divide) is through modified gravity. A key point is to not view the expansion history in isolation but to take into account the other gravitational impacts on growth of large scale structure, lensing, etc. Within shift symmetric Horndeski gravity this implies three main paths for the late time cosmic expansion. All require unusual kinetic structure and we analyze their various implications for how $w$ should behave after phantom crossing.
Read the full abstract

High Energy Astrophysical Phenomena

GRB 230204B: GIT Discovery of a Fast Fading Afterglow Associated with an Energetic GRB from a Massive-Star Progenitor

Vishwajeet Swain, Varun Bhalerao, Harsh Kumar et al. (+19 more)

We present a comprehensive multi-wavelength study of a bright gamma-ray burst GRB 230204B, analyzing both prompt and afterglow emissions. This GRB is highly energetic, with an isotropic equivalent energy emission $E_{\mathrm{iso}} \sim 2.2 \times 10^{54}\ \mathrm{erg}$, released during the prompt emission. The GROWTH-India Telescope discovered a bright afterglow ($m_r = 15.55$) that faded rapidly ($\propto t^{-1.82}$). The prompt emission shows strong thermal photospheric emission, along with a non-thermal high-energy component. We explore the evolution of these components and find them to be consistent with theoretical expectations. Afterglow modeling reveals an energetic jet $E_{tot} \gtrsim 10^{52}\ \mathrm{erg}$ expanding into a wind-type medium viewed nearly on-axis, suggesting a massive star progenitor with strong winds. We also explore correlations between the prompt emission and afterglow that may help to understand the complete picture of GRB progenitors.
Read the full abstract

All authors Vishwajeet Swain, Varun Bhalerao, Harsh Kumar, Mehul Goyal, Ankur Ghosh, Utkarsh Pathak, Poonam Chandra, Tomas Ahumada, G. C. Anupama, Suman Bala, Sudhanshu Barway, Joshua S. Bloom, Dimple Dimple, Viraj R. Karambelkar, Mansi M. Kasliwal, Kuntal Misra, Josiah Purdum, Divita Saraogi, Jesper Sollerman, Aswin Suresh, Stefan J. van der Walt, Gaurav Waratkar

Cosmology and Nongalactic Astrophysics

The Mass-Metallicity Relation and its Observational Effects at z~3-6

Zach Lewis, Michael V. Maseda, Anna de Graaff et al. (+21 more)

The correlation between galaxy stellar mass and gas-phase metallicity, known as the mass-metallicity relation (MZR), gives key insights into the processes that govern galaxy evolution. However, unquantified observational and selection biases can result in systematic errors in attempts to recover the intrinsic MZR, particularly at higher redshifts. We characterize the MZR at z~3-6 within a fully Bayesian framework using JWST NIRSpec spectra of 193 galaxies from the RUBIES survey. We forward model the observed mass-metallicity surface using prospector-generated spectra to account for two selection biases: the survey selection function and success in observing high signal-to-noise emission lines. We demonstrate that the RUBIES selection function, based on F444W magnitude and F150W-F444W color, has a negligible effect on our measured MZR. A correct treatment of the non-Gaussian metallicity uncertainties from strong-line calibrations lowers the derived MZR normalization by 0.2 dex and flattens the slope by ~20%; forward-modeling the effect of emission line observability steepens the slope by ~15%. Both of these biases must be taken into account in order to properly measure the intrinsic MZR. This novel forward modeling process motivates careful consideration of selection functions in future surveys, and paves the way for robust, high-redshift chemical enrichment studies that trace the evolution of the mass-metallicity relation across cosmic time.
Read the full abstract

All authors Zach Lewis, Michael V. Maseda, Anna de Graaff, Joel Leja, Bingjie Wang, Hans-Walter Rix, Ian McConachie, Nikko J. Cleri, Rachel Bezanson, Leindert A. Boogaard, Gabriel Brammer, Jenny E. Greene, Michaela Hirschmann, Harley Katz, Ivo Labbe, Jorryt Matthee, Tim B. Miller, Rohan P. Naidu, Pascal A. Oesch, David J. Setton, Katherine A. Suess, Andrea Weibel, Katherine E. Whitaker, Christina C. Williams

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

A Thermal Relic Encyclopedia: Dark Matter Candidates Coupled to Quarks

Dan Hooper, Gordan Krnjaic, Tanner Trickle et al. (+1 more)

Thermal freeze-out is a compelling framework for naturally generating the dark matter abundance. We systematically study a broad range of dark matter and mediator particle combinations that can viably realize thermal freeze-out, focusing on models in which the mediator couples to Standard Model quarks. In each case, we calculate the relic density and consider existing constraints from accelerators, cosmology, direct detection, and indirect detection over the full range of dark matter and mediator masses. We present an encyclopedic catalog of matrix elements, cross sections, and decay rates which can be used as a reference for future studies of dark matter phenomenology.
Read the full abstract

All authors Dan Hooper, Gordan Krnjaic, Tanner Trickle, Isaac R. Wang

Astrophysics of Galaxies

The DREAMS Project: Disentangling the Impact of Halo-to-Halo Variance and Baryonic Feedback on Milky Way Dark Matter Density Profiles

Alex M. Garcia, Jonah C. Rose, Paul Torrey et al. (+23 more)

In this work, we utilize a new suite of Milky Way-mass halos from the DREAMS Project, simulated with Cold Dark Matter (CDM), to quantify the influence of baryon feedback and intrinsic halo-to-halo variance on dark matter density profiles. Our suite of 1024 halos varies over supernova and black hole feedback parameters from the IllustrisTNG model, as well as variations in two cosmological parameters. We find that, for the DREAMS parameter variations, Milky Way-mass dark matter density profiles in the IllustrisTNG model are largely insensitive to astrophysics and cosmology variations, with the dominant source of scatter instead arising from halo-to-halo variance. However, most of the (comparatively minor) feedback-driven variations come from the changes to supernova prescriptions. By comparing to dark matter-only simulations, we find that the strongest supernova wind energies are so effective at preventing galaxy formation that the halos are nearly entirely collisionless dark matter. Finally, regardless of physics variation, all the DREAMS halos are roughly consistent with a halo contracting adiabatically from the presence of baryons, unlike models that have bursty stellar feedback. This work represents a step toward assessing the uncertainty in Milky Way dark matter profiles, with direct implications for dark matter searches where systematic uncertainty in the density profile remains a major challenge.
Read the full abstract

All authors Alex M. Garcia, Jonah C. Rose, Paul Torrey, Andrea Caputo, Mariangela Lisanti, Andrew B. Pace, Hongwan Liu, Abdelaziz Hussein, Haozhe Liu, Francisco Villaescusa-Navarro, John Barry, Ilem Leisher, Belén Costanza, Jonathan Kho, Ethan Lilie, Jiaxuan Li, Niusha Ahvazi, Aklant Bhowmick, Tri Nguyen, Stephanie O'Neil, Xiaowei Ou, Xuejian Shen, Arya Farahi, Nitya Kallivayalil, Lina Necib, Mark Vogelsberger

Astrophysics of Galaxies

A Critical Evaluation of the Physical Nature of the Little Red Dots

Kohei Inayoshi and Luis C. Ho

Little Red Dots (LRDs) are a newly identified class of active galactic nuclei (AGNs) uncovered by JWST deep surveys. Their enigmatic properties challenge the canonical AGN paradigm and have stimulated ideas on early massive black hole (BH) formation. In this review, we summarize how early BHs shape the characteristic features of LRDs, how their nuclear environments differ from those of normal AGNs, and how future observations can distinguish between competing scenarios. Our main conclusions are as follows: (1) LRDs show broad-line emission consistent with mass accretion onto BHs with $M_{\rm BH}\simeq 10^{6-7}~M_\odot$, suggesting that AGN activity is a plausible origin of their dominant red optical emission. (2) Stellar components can reproduce the continuum energetics through dusty star formation. However, the required stellar mass would be too large to remain consistent with other LRD properties. Therefore, a purely stellar origin is unlikely to be the dominant power source, although star formation may still contribute to the UV emission. (3) The coexistence of broad-line emission with Balmer absorption and break features on LRD spectra, neither of which can be explained by stellar populations, suggests that nuclear BHs are enshrouded by dense gas with a high covering fraction. (4) Gas-enshrouded AGNs can produce red optical spectra without requiring dust reddening through a combination of gas attenuation and thermal self-emission with an effective temperature of $T_{\rm eff}\simeq 5000~{\rm K}$, which also accounts for the flat infrared continuum. (5) From the spectral features and redshift evolution, LRDs are likely a transient phase in early BH growth, possibly the first accretion episodes of newborn BHs. (6) Testing models for LRD spectra and origins through time variability, ionizing sources, post-LRD objects, and low-redshift analogs is particularly promising.
Read the full abstract

High Energy Astrophysical Phenomena

Taming the Tarantula: How Stellar Wind Feedback Shapes Gas and Dust in 30 Doradus

Jennifer A. Rodriguez, Laura A. Lopez, Lachlan Lancaster et al. (+5 more)

Observations of massive star-forming regions show that classical stellar wind models over-predict the luminosity of the X-ray emitting gas, indicating a significant fraction of wind energy is lost. In this paper, we present a multi-wavelength analysis of the giant HII region 30 Doradus and its central star cluster R136 using 2 Ms of Chandra X-ray Observatory data, combined with James Webb Space Telescope and Hubble Space Telescope imaging and Spitzer spectral-energy distributions, to investigate how the hot gas energy is lost through turbulent mixing, radiative cooling, and physical leakage. We compare the spatial and spectral properties of the hot gas with those of the warm ionized gas and dust. We find no significant correlation between the dust and hot gas temperatures, suggesting they are not directly coupled and that the dust resides in the swept-up shells where it is heated radiatively. H$\alpha$ and X-ray surface brightness profiles show that the X-rays peak interior to the H$\alpha$ shells, demonstrating partial confinement of the hot gas. The fragmented shell structure and bright X-ray interior that declines near the H$\alpha$ shell reflect efficient cooling from turbulent mixing at the hot-cold interface. We compare against recent simulations of stellar-feedback driven bubbles which have broad agreement with the morphology of the X-ray and H$\alpha$ emission, but the simulations produce a dip in the interior X-ray surface brightness and a lack of hard X-rays compared to the observations. These differences may suggest thermal conduction is important as mass-loading of the hot bubble could reproduce the X-ray observables.
Read the full abstract

All authors Jennifer A. Rodriguez, Laura A. Lopez, Lachlan Lancaster, Anna L. Rosen, Omnarayani Nayak, Sebastian Lopez, Tyler Holland-Ashford, Trinity L. Webb

Earth and Planetary Astrophysics

Characterization of debris disks observed with SPHERE

N. Engler, J. Milli, N. Pawellek et al. (+33 more)

This study aims to characterize debris disks observed with SPHERE across multiple programs, with the goal of identifying systematic trends in disk morphology, dust mass, and grain properties as a function of stellar parameters. We analyzed a sample of 161 young stars using SPHERE observations at optical and near-IR wavelengths. Disk geometries were derived from ellipse fitting and model grids, while dust mass and properties were constrained by modified blackbody (MBB) and size distribution (SD) modeling of SEDs. The dynamical modeling was performed to assess whether the observed disk structures can be explained by the presence of unseen planets. We resolved 51 debris disks, including four new detections: HD 36968, BD-20 951, and the inner belts of HR 8799 and HD 36546. In addition, we found a second transiting giant planet in the HD 114082 system, with a radius of 1.29 $R_{\rm Jup}$ and an orbital distance of ~1 au. We identified nine multi-belt systems, with outer-to-inner belt radius ratios of $1.5-2$, and found close agreement between scattered-light and millimeter-continuum belt radii. They scale weakly with stellar luminosity ($R_{\rm belt} \propto L_{\star}^{0.11}$), but show steeper dependencies when separated by CO and CO$_2$ freeze-out regimes. Disk fractional luminosities follow collisional decay trends, declining as $t_{\rm age}^{-1.18}$ for A and $t_{\rm age}^{-0.81}$ for F stars. The inferred dust masses span $10^{-5}-1\,M_\oplus$ from MBB and $0.01-1\,M_\oplus$ from SD modeling. These masses scale as $R_{\rm belt}^n$ with $n>2$ in belt radius and super-linearly with stellar mass, consistent with trends seen in protoplanetary disks. Analysing correlation between disk polarized flux and IR excess, we found an offset of ~1 dex between total-intensity (HST) and polarized fluxes. A new parametric approach to estimate dust albedo and maximum polarization fraction is introduced.
Read the full abstract

All authors N. Engler, J. Milli, N. Pawellek, R. Gratton, P. Thébault, C. Lazzoni, J. Olofsson, H. M. Schmid, S. Ulmer-Moll, C. Perrot, J.-C. Augereau, S. Desidera, G. Chauvin, M. Janson, C. Xie, Th. Henning, A. Boccaletti, S. B. Brown-Sevilla, E. Choquet, C. Dominik, M. Samland, A. Zurlo, M. Feldt, T. Fusco, C. Ginski, J. H. Girard, D. Gisler, R. G. van Holstein, A.-M. Lagrange, M. Langlois, A.-L. Maire, D. Mesa, P. Rabou, L. Rodet, T. Schmidt, A. Vigan

Solar and Stellar Astrophysics

Enhanced magnetostrophic waves with magnetic field orthogonal to the rotation axis

Raviraj Narayan Shinde and Ghanesh Narasimhan

We consider an isolated Gaussian velocity vortex perturbation in an otherwise quiescent, electrically conducting, and rotating fluid permeated by a uniform magnetic field $\bf{B}$. Studies suggest a presence of strong azimuthal wave motions on the timescale of centuries within the Earth's liquid outer core at higher latitudes. To understand these long-period oscillations, we focus on magnetostrophic waves, a slow component of magnetic-Coriolis waves with $\bf{B}$ orthogonally aligned with the rotation vector $\bf{\Omega}$, which replicate the field lines in the azimuthal direction. We present an analytical solution to the magnetic-Coriolis wave equation in Cartesian coordinates. Later, with numerical solution, we validate our analytical estimates and show that magnetostrophic waves travel relatively faster along the magnetic field when $\bf{B} \perp \bf{\Omega}$ compared with the case when both are aligned. The study confirms that with a magnetic field $\bf{B}$ orthogonally aligned to the rotation vector $\bf{\Omega}$, wave vectors satisfying the condition $\bf{\Omega}\cdot\bf{k} \approx 0$, travel with Alfvén velocities along the magnetic field lines as a component of inertial-Alfvén waves. The timescales on which Alfvén waves travel are relatively short, and it is also less likely that inertial-Alfvén waves will be sustained inside the core at higher latitudes \citep{Davidson2017}. This study shows that, excluding the inertial-Alfvén waves contribution ($k_z\neq 0$), there exists intensified magnetostrophic wave propagation when $\bf{B} \perp \bf{\Omega}$, which can explain the strong periodic oscillations on the time scales of centuries along the azimuthal field at higher latitudes. Results show persistence of the magnetostrophic waves despite the lower Lehnert number $Le$, suggesting the plausible existence of a low-intensity azimuthal magnetic field in the Earth's core.
Read the full abstract

Earth and Planetary Astrophysics · Cross-listed from physics.ao-ph

An infrasound source analysis of the OSIRIS-REx sample return capsule hypersonic re-entry

Jordan W. Bishop, Philip Blom, Chris Carr et al. (+1 more)

The OSIRIS-REx sample return capsule hypersonic re-entry into the atmosphere is a rare opportunity to test a variety of sonic boom source models since the projectile dimensions are well characterized. While the as-flown flight path is unknown, the predicted flight path enables a rough approximation of the source Mach number and location. Six infrasound microphones deployed in the boom carpet along the predicted flight path recorded impulsive signals from the OSIRIS-REx re-entry. Using a suite of atmosphere profiles and the geometric acoustics approximation, we estimate locations with uncertainty estimates along the flight path from which the signals were emitted. Acoustic overpressure and signal duration predictions from Whitham's far field theory, Carlson's simplified sonic boom prediction method, and a drag-dominated hypersonic model are analyzed with uncertainty estimates from the location estimate. While the Carlson simplified sonic boom prediction method could be accurate, our preference is for the drag-dominated source model. Using this source model with an inviscid Burgers' equation solver for propagation, we obtained an excellent match to the recorded data. These results will help better inform future sample return capsule re-entry observation campaigns as well as contribute to a better understanding of high altitude infrasonic sources.
Read the full abstract

All authors Jordan W. Bishop, Philip Blom, Chris Carr, Jeremy Webster

Earth and Planetary Astrophysics · Cross-listed from gr-qc

Probing for primordial black hole candidates in exoplanet search data

Paul Halpern, Erik Cauley, Max Stoltzmann et al. (+1 more)

We have sifted through astrophysical data collected by various radial velocity and gravitational microlensing searches for exoplanets with the goal of identifying potential signs of the presence of primordial black holes (PBH). Our motivation is that those hypothesized remnants of inhomogeneous energetic fluctuations in the early universe, though too small for direct detection, are thought to have a mass range similar to that of planets. Thereby, if captured by stars, they could conceivably make their presence known through stellar wobbles picked up by means of Doppler spectroscopy in the radial velocity method, or alternatively through microlensing. In our analysis of such data, we have identified potential PBH contenders by ruling out any exoplanet candidates that have been detected through direct imaging or transit methods, as they would have sizes consistent with planets rather than PBHs. In particular we focus on the objects Kepler-21 Ac, HD 219134 f, Gliese 686 b, HR 5183 b, HD 20794 e, and Wolf 1061 d, each of which has been found using the radial velocity method but never imaged (either directly or through transit). We also examine the microlensing events MOA 2009-BLG-387L and OGLE-2016-BLG-1540, which offer promise as candidate PBHs. We present these as a representative, but not exclusive list, of potential PBH contenders. Furthermore, future imaging, especially focused on signals of planetary dimensions versus evaporation signatures, might clarify which of these are indeed exoplanets.
Read the full abstract

All authors Paul Halpern, Erik Cauley, Max Stoltzmann, Mauritz Wilshusen

Cosmology and Nongalactic Astrophysics

A new constraint on the $y$-distortion with FIRAS: implications for feedback models in galaxy formation and cosmic shear measurements

Giulio Fabbian, Federico Bianchini, Alina Sabyr et al. (+4 more)

The $y$-type distortion of the blackbody spectrum of the cosmic microwave background radiation probes the pressure of the gas trapped in galaxy groups and clusters. We reanalyze archival data of the FIRAS instrument with an improved astrophysical foreground cleaning technique, and measure a mean $y$-distortion of $\langle y\rangle = (1.2\pm 2.0) \times 10^{-6}$ ($\langle y\rangle\lesssim 5.2\times 10^{-6}$ at 95% C.L.), a factor of $\sim 3$ tighter than the original FIRAS results. This measurement directly rules out many models of baryonic feedback as implemented in cosmological hydrodynamical simulations, mostly using information in objects with mass $M\lesssim 10^{14} {\rm M}_{\odot}$. We discuss its implications for the analysis of cosmic shear and kinetic Sunyaev-Zel'dovich effect data, and future spectral distortion experiments.
Read the full abstract

All authors Giulio Fabbian, Federico Bianchini, Alina Sabyr, J. Colin Hill, Christopher C. Lovell, Leander Thiele, David N. Spergel

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Neutron stars in $f(\mathbb{Q})$ gravity

Lavinia Heisenberg and Carlos Pastor-Marcos

We investigate the challenges of constructing neutron star (NS) solutions in $f(\mathbb{Q})$ gravity, highlighting the importance of treating the affine connection as an active, dynamical component of the theory. We begin by clarifying under what conditions standard simplifications – such as the coincident gauge or General Relativity (GR)-like connections – inadvertently lead to GR behavior, even in non-trivial $f(\mathbb{Q})$ models. Building on previous work in black hole (BH) spacetimes, we adapt the formalism to NS and extend it to non-vacuum configurations. Focusing on two representative models, $f(\mathbb{Q}) = \mathbb{Q} + \alpha \mathbb{Q}^2$ and $f(\mathbb{Q}) = \mathbb{Q}^\beta$, our analysis suggests that, under standard regularity assumptions, solutions with Maclaurin/Laurent-type series recover GR dynamics, pointing to more intricate structures as the likely seat of beyond-GR effects, and reflecting the constraints imposed by the connection's dynamics on the asymptotic behavior of genuinely beyond-GR solutions. We then formulate the problem as a boundary value problem (BVP) and highlight the numerical pathologies that may arise, together with possible strategies to prevent them. This work aims to provide a concrete framework for future numerical studies and outlines the theoretical consistency conditions required to construct physically meaningful beyond-GR NS solutions in $f(\mathbb{Q})$ gravity.
Read the full abstract

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Topological Shell Structures in Neutron Stars: Effects on Equilibrium, Oscillations, and Gravitational-Wave Signatures

Debojoti Kuzur and Kamal Krishna Nath

We study the structural and dynamical consequences of introducing a distributional density profile inside a neutron star, representing a massless, topological shell located at an arbitrary radius. We incorporate this effect into the structure of neutron star and construct equilibrium sequence for several realistic equations of state. Radial stability is examined through the Sturm-Liouville formulation of the $\ell=0$ perturbation equation, supplemented with a jump condition and imprinting distinct features on the fundamental $f$-mode spectrum. We find strong, non-monotonic variations in the mode frequency relative to standard no-shell models. Using first-principles scaling relations, we estimate various gravitational wave observables such as the damping time, quality factor, luminosity and characteristic strain. These observables are then compared with the sensitivity of Advanced LIGO, and third-generation detectors such as the Einstein Telescope and Cosmic Explorer. Our results demonstrate that internal topological shells can leave potentially observable signatures in the oscillation and gravitational wave properties of neutron stars.
Read the full abstract

Astrophysics of Galaxies · Cross-listed from hep-ph

Modeling dark matter halos with self-interacting fermions: A polytropic approach

Fabian Hernandez-Gutierrez and Juan Barranco

In this work we study the possibility of modeling the dark matter content in galaxies as a core-halo model consisting of self-gravitating, self-interacting fermions by means of an effective polytropic equation of state. For the core of the halo, the dark matter fermions are degenerate, while for the halo we have considered two possibilities: the fermions have thermalized as a perfect fluid, or they will follow a standard cold dark matter Navarro-Frenk-White profile. The core density profile is obtained by solving the Tolman-Oppenheimer-Volkoff equations, and their properties are determined by the fermion mass, the central density and the interaction strength. The mass of the fermion and the strength of the fermion self-interaction is fixed by doing a $\chi^2$ analysis to fit that fit the rotational curves of Low Surface Brightness galaxies. It was found that the fermion mass should be in the range $155.10~\rm{eV}< m_{f} < 313.26~\rm{eV}$ and the interparticle strength in the range $1465.31 < y <6002.04$ at $68$ C.L. in order to reproduce the rotational curves adequately, in the case when the halo is modeled as a thermalized ideal gas. Similar values are obtained if the halo is modeled following a Navarro-Frenk-White case, namely $42.31 ~\rm{eV} < m_{f} <49.23 ~\rm{eV}$ and $71.43< y < 132.65$. Once fixed the values of the mass of the fermion $m_f$ and the interaction strength $y$, we tested the core-halo model with data from the Milky Way, local dwarf spheroidal galaxies and the SPARC database. We have found good agreement between the data and the core-halo models, varying only one free parameter: the central density. Thus a single fermion can fit hundreds of galaxies. Nevertheless, the dark matter halo surface density relation or the halo total mass and radius depend strongly on the model for the halo.
Read the full abstract

Astrophysics of Galaxies

MIRI spectrophotometry of GN-z11: Detection and nature of an optical red continuum component

A. Crespo Gómez, L. Colina, P. G. Pérez-González et al. (+16 more)

We present new MIRI F560W, F770W and F1000W imaging of GN-z11, extending the previous rest-frame coverage from 0.38 to 0.86$\mu$m. We report significant detections (14$\sigma$) in the F560W and F770W images, and a marginal detection (3.2$\sigma$) in F1000W. Here, we analyse its SED combining new MIRI imaging data with archival NIRSpec/Prism and MRS spectroscopy, and NIRCam imaging. The continuum emission shows a flat energy distribution, in f$_\nu$, up to 0.5$\mu$m, compatible with the presence of a mixed stellar population of young (4$\pm$1 Myr) and mature (63$\pm$23 Myr) stars that also account for the [O III], H$\beta$ and H$\alpha$ emission lines. The continuum at rest-frame 0.66$\mu$m shows a 36$\pm$3% flux excess above the predicted flux for a mixed stellar population, pointing to the presence of an additional source contributing at these wavelengths. This excess increases to 91$\pm$28% at rest-frame 0.86$\mu$m, although with a large uncertainty due to the marginal detection in the F1000W filter. We consider that hot dust emission in the dusty torus around a type 2 AGN could be responsible for the observed excess. Alternatively, this excess could be due to hot dust emission or to a photoluminiscence dust process (Extended Red Emission, ERE) under the extreme UV radiation field, as observed in some local metal-poor galaxies and in young compact starbursts. The presence of a type 1 AGN is not supported by the observed SED since high-z QSOs contribute at wavelengths above rest-frame 1$\mu$m, and an additional ad-hoc red source would be required to explain the observed flux excess at 0.66 and 0.86$\mu$m. Additional deep MIRI imaging covering the rest-frame near-IR are needed to confirm the flux detection at 10$\mu$m with higher significance, and to discriminate between the different hot dust emission in the extreme starburst and AGN scenarios with MIRI imaging at longer wavelengths.
Read the full abstract

All authors A. Crespo Gómez, L. Colina, P. G. Pérez-González, J. Álvarez-Márquez, M. García-Marín, A. Alonso-Herrero, M. Annunziatella, A. Bik, S. Bosman, A. J. Bunker, A. Labiano, D. Langeroodi, P. Rinaldi, G. Östlin, L. Boogaard, S. Gillman, G. Barro, S. L. Finkelstein, G. C. K. Leung

Astrophysics of Galaxies

The Composite Spectrum of QSO Absorption Line Systems in DESI DR2

Lucas Napolitano, Adam D. Myers, Adam Tedeschi et al. (+43 more)

We present details regarding a composite spectrum of quasar (QSO) absorption line systems. In this composite spectrum we identify more than 70 absorption lines, and observe oxygen and hydrogen emission features at a higher signal-to-noise ratio than any previous study. As the light from a distant quasar travels towards an observer, it may interact with the circumgalactic medium of an intervening galaxy, forming absorption lines. In order to maximize the signal of these absorption lines, we have selected a sample of 239,174 quasar spectra from the second data release of the Dark Energy Spectro- scopic Instrument (DESI), each identified to have absorption lines resulting from such an interaction. By stacking these spectra in the restframe of the absorption, and calculating a median composite spec- trum, we are able to isolate and enhance these absorption lines. We provide a full atlas of all detected absorption and emission lines as well as their fit centroids and equivalent width values. We additionally provide analysis of composites constructed using subsamples of absorbers in both redshift and Mg II equivalent width bins. We find that there is minimal redshift evolution across the considered absorber samples. Additionally, we find that dense gas signatures, such as the presence of Na I absorption, are strongest in the highest equivalent width absorber sample, and that the strengths of the Si IV and C IV absorption lines show a relatively weak correlation with Mg II equivalent width. This atlas should aid in future studies investigating the compositions and physical conditions of these absorbers.
Read the full abstract

All authors Lucas Napolitano, Adam D. Myers, Adam Tedeschi, Abhijeet Anand, Hiram K. Herrera-Alcantar, Jessica Aguilar, Steven Ahlen, Stephen Bailey, Segev BenZvi, Davide Bianchi, David Brooks, Todd Claybaugh, Andrei Cuceu, Axel de la Macorra, Arjun Dey, Biprateep Dey, Peter Doel, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztanaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Julien Guy, Dick Joyce, Anthony Kremin, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, Ramon Miquel, John Moustakas, Seshadri Nadathur, Nathalie Palanque-Delabrouille, Will Percival, Francisco Prada, Ignasi Perez-Rafols, Graziano Rossi, Eusebio Sanchez, David Schlegel, Michael Schubnell, Joesph Harry Silber, David Sprayberry, Gregory Tarle, Benjamin Alan Weaver, Rongpu Zhou, Hu Zou

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th

Singular $\alpha$-attractors

Renata Kallosh and Andrei Linde

$\alpha$-attractor models naturally appear in supergravity with hyperbolic geometry. The simplest versions of $\alpha$-attractors, T- and E-models, originate from theories with non-singular potentials. In canonical variables, these potentials have a plateau that is approached exponentially fast at large values of the inflaton field $\varphi$. In a closely related class of polynomial $\alpha$-attractors, or P-models, the potential is not singular, but its derivative is singular at the boundary. The resulting inflaton potential also has a plateau, but it is approached polynomially. In this paper, we will consider a more general class of potentials, which can be singular at the boundary of the moduli space, S-models. These potentials may have a short plateau, after which the potential may grow polynomially or exponentially at large values of the inflaton field. We will show that this class of models may provide a simple solution to the initial conditions problem for $\alpha$-attractors and may account for a very broad range of possible values of $n_{s}$ matching the recent ACT, SPT, and DESI data.
Read the full abstract

Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc

Flexible Gravitational-Wave Parameter Estimation with Transformers

Annalena Kofler, Maximilian Dax, Stephen R. Green et al. (+6 more)

Gravitational-wave data analysis relies on accurate and efficient methods to extract physical information from noisy detector signals, yet the increasing rate and complexity of observations represent a growing challenge. Deep learning provides a powerful alternative to traditional inference, but existing neural models typically lack the flexibility to handle variations in data analysis settings. Such variations accommodate imperfect observations or are required for specialized tests, and could include changes in detector configurations, overall frequency ranges, or localized cuts. We introduce a flexible transformer-based architecture paired with a training strategy that enables adaptation to diverse analysis settings at inference time. Applied to parameter estimation, we demonstrate that a single flexible model, called Dingo-T1, can (i) analyze 48 gravitational-wave events from the third LIGO-Virgo-KAGRA Observing Run under a wide range of analysis configurations, (ii) enable systematic studies of how detector and frequency configurations impact inferred posteriors, and (iii) perform inspiral-merger-ringdown consistency tests probing general relativity. Dingo-T1 also improves median sample efficiency on real events from a baseline of 1.4% to 4.2%. Our approach thus demonstrates flexible and scalable inference with a principled framework for handling missing or incomplete data, key capabilities for current and next-generation observatories.
Read the full abstract

All authors Annalena Kofler, Maximilian Dax, Stephen R. Green, Jonas Wildberger, Nihar Gupte, Jakob H. Macke, Jonathan Gair, Alessandra Buonanno, Bernhard Schölkopf

Cosmology and Nongalactic Astrophysics

The suppression of the matter power spectrum: strong feedback from X-ray gas mass fractions, kSZ effect profiles, and galaxy-galaxy lensing

Jared Siegel, Leah Bigwood, Alexandra Amon et al. (+6 more)

Baryon feedback redistributes gas relative to the underlying dark matter distribution and suppresses the matter power spectrum on small scales, but the amplitude and scale dependence of this effect are uncertain. We constrain the impact of baryon feedback on the matter power spectrum by jointly analysing X-ray gas mass fractions from the eROSITA and HSC-XXL samples and SDSS/DESI+ACT kinetic Sunyaev-Zel'dovich (kSZ) effect profiles; the samples are characterised with galaxy-galaxy lensing and together span group and cluster masses at $0<z<1$. Using the baryonification framework, our joint eROSITA and kSZ model gives precise constraints on the suppression of the matter power spectrum: $10 \pm 2\%$ at $k=1~h~\mathrm{Mpc}^{-1}$. The inferred gas profiles are more extended and the power suppression is stronger than predicted by the fiducial models of recent hydrodynamical simulation suites, including FLAMINGO and BAHAMAS. The HSC-XXL gas mass fractions, which the fiducial simulations were calibrated to reproduce, prefer more moderate power suppression than the kSZ and eROSITA data: $5 \pm 4\%$ at $k=1~h~\mathrm{Mpc}^{-1}$. With a simulated LSST Year 1 weak lensing analysis, we demonstrate a framework for next-generation surveys: calibrating feedback models with multi-wavelength gas observables to recover the small-scale statistical power of cosmic shear.
Read the full abstract

All authors Jared Siegel, Leah Bigwood, Alexandra Amon, Jamie McCullough, Masaya Yamamoto, Ian G. McCarthy, Matthieu Schaller, Aurel Schneider, Joop Schaye

Astrophysics of Galaxies

Distinguishing ram pressure from gravitational interactions: Applying the Size-Shape Difference method to real galaxies

Augusto E. Lassen, Rory Smith, Benedetta Vulcani et al. (+12 more)

In dense environments, mechanisms like ram pressure stripping (RPS) and gravitational interactions can induce similar morphological features in galaxies, distinguishable only through detailed study of their stellar properties. While RPS affects recently formed stars by displacing the gas disk from which they form, gravitational interactions perturb stars of all ages rather similarly. We present the first observational test of the Size-Shape Difference (SSD) measure, a novel approach validated for simulated galaxies, that quantifies morphological differences between young and intermediate-age stellar populations to distinguish RPS from gravitationally interacting galaxies. We analyze 67 galaxies from the GASP survey using spatially-resolved star formation histories derived using SINOPSIS. In our fiducial model, we compare stellar populations in two age bins (t < 20 Myr and 20 Myr <= t < 570 Myr) to calculate SSD values. The sample includes confirmed RPS cases with different stripping intensities, as well as undisturbed and gravitationally interacting galaxies. We find that extreme cases of RPS show SSD values ~3.5x higher than undisturbed and gravitationally interacting galaxies (56(+24/-15) as compared to 16(+6/-2) and 16(+6/-3), respectively), confirming simulation predictions. This enhancement reflects RPS-induced asymmetries: youngest stars are compressed along the leading edge and/or displaced into the extended tails of cold gas, while older populations remain undisturbed. In contrast, gravitational interactions perturb all stars uniformly, producing lower SSD values. SSD robustly distinguishes strong RPS cases, even adopting different age bins. This holds even without correcting for disk inclination, or when single-band imaging are used to trace stellar distributions. This makes SSD a promising tool to select RPS candidates for spectroscopic follow-up in upcoming surveys.
Read the full abstract

All authors Augusto E. Lassen, Rory Smith, Benedetta Vulcani, Stephanie Tonnesen, Paula Calderón-Castillo, Bianca M. Poggianti, Jacopo Fritz, Koshy George, Alessandro Ignesti, Yara Jaffé, Antonino Marasco, Luka Matijevič, Alessia Moretti, Mario Radovich, Neven Tomičič

High Energy Astrophysical Phenomena

Insights into Extragalactic Background Light constraints with MAGIC archival data

R. Grau and A. Moralejo

The Extragalactic Background Light (EBL) is the accumulated light emitted throughout the history of the universe, spanning the UV, optical, and IR spectral ranges. Stars and dust in galaxies are expected to be the main source of the EBL. However, recent direct measurements performed beyond Pluto's orbit (less affected by foregrounds than those performed from the Earth) hint at an EBL level in the optical band larger than the one expected from the integrated contribution of known galaxy populations. One approach that could solve this controversy uses Very High Energy (VHE) photons coming from sources at cosmological distances. These photons can interact with the EBL producing electron-positron pairs, a process that leaves an imprint on the observed VHE spectrum. This technique, however, requires assumptions on the intrinsic spectrum of the source, which can compromise the robustness of EBL constraints. In this contribution, we used Monte Carlo simulations and archival data of the MAGIC telescopes to study the impact that the assumptions adopted in the literature have on the estimate of the EBL density, and how using more generic ones would modify the results. Our results show how the EBL density constraints obtained highly depend on the intrinsic spectral shape assumed for the source. We have studied two different methods to reduce the assumptions on the intrinsic spectral shape to get more robust results. This will be especially important for upcoming with new VHE facilities, where systematic uncertainties are expected to play a more significant role compared to statistical ones.
Read the full abstract

Astrophysics of Galaxies · Cross-listed from physics.hist-ph

Limiting Reduction and Modified Gravity

Antonis Antoniou and Lorenzo Lorenzetti

Modified Newtonian Dynamics (MOND) is a framework of theories that adjust Newton's laws of gravity to explain effects such as galactic rotation anomalies, offering an alternative to dark matter. This essay examines the justification of MOND by assessing its inter-theoretical relationship to established theories across relevant scales, in particular its connection to Newtonian gravitation. We argue that MOND fails a key condition for a theory's justification–what we call 'reduction-wise justification'–since it does not adequately reduce to Newtonian gravity in a fully non-arbitrary way. More precisely, despite satisfying the standard formal criteria for successful limiting reduction, MOND does not properly reduce to Newtonian gravitation because of (i) the absence of a fundamental theoretical framework to justify the interpolating function introduced in MOND and (ii) the lack of a unified mathematical structure working across all scales, independent of Newtonian theory. Hence, the case study of MOND provides crucial results for the general debate on inter-theoretic reduction in science: MOND's failure as a case of reduction highlights important limitations in standard accounts of limiting reduction. We respond by proposing a more refined framework for limiting reduction that introduces two additional criteria to better distinguish successful from pathological reductions. More broadly, this case illustrates how analysing reduction-wise justification can serve as a powerful tool for evaluating the validity of novel theories that are not yet empirically established.
Read the full abstract